Derive: Lists requires child type to implement FromStr and Display, which are not implemented

[tobz1000]

Attempting to generate types for this .xsd:
https://docs.oasis-open.org/odata/odata-csdl-xml/v4.01/os/schemas/edm.xsd

I get the compile errors:

error[E0277]: the trait bound `TPath: std::str::FromStr` is not satisfied
  --> src\main.rs:15:17
   |
15 | #[derive(Debug, XmlSchema)]
   |                 ^^^^^^^^^ the trait `std::str::FromStr` is not implemented for `TPath`
   |
   = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0599]: no method named `to_string` found for reference `&TPath` in the current scope
  --> src\main.rs:15:17
   |
15 | #[derive(Debug, XmlSchema)]
   |                 ^^^^^^^^^
   |                 |
   |                 method not found in `&TPath`
   |                 doesn't satisfy `TPath: std::fmt::Display`
   |                 doesn't satisfy `TPath: std::string::ToString`
   |
   = note: the method `to_string` exists but the following trait bounds were not satisfied:
           `TPath: std::fmt::Display`
           which is required by `TPath: std::string::ToString`
           `&TPath: std::fmt::Display`
           which is required by `&TPath: std::string::ToString`
   = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)

The relevant generated code looks like (note the .parse() and .to_string()):

#[derive(Clone, Debug, Default, PartialEq)]
pub struct TEnumMemberList {
    items: Vec<TPath>,
}
impl YaDeserialize for TEnumMemberList {
    fn deserialize<R: Read>(reader: &mut yaserde::de::Deserializer<R>) -> Result<Self, String> {
        loop {
            match reader.next_event()? {
                xml::reader::XmlEvent::StartElement { .. } => {}
                xml::reader::XmlEvent::Characters(ref text_content) => {
                    let items: Vec<TPath> = text_content
                        .split(' ')
                        .map(|item| item.to_owned())
                        .map(|item| item.parse().unwrap())
                        .collect();
                    return Ok(TEnumMemberList { items });
                }
                _ => {
                    break;
                }
            }
        }
        Err("Unable to parse attribute".to_string())
    }
}
impl YaSerialize for TEnumMemberList {
    fn serialize<W: Write>(&self, writer: &mut yaserde::ser::Serializer<W>) -> Result<(), String> {
        let content = self
            .items
            .iter()
            .map(|item| item.to_string())
            .collect::<Vec<String>>()
            .join(" ");
        let data_event = xml::writer::XmlEvent::characters(&content);
        writer.write(data_event).map_err(|e| e.to_string())?;
        Ok(())
    }
    fn serialize_attributes(
        &self,
        mut source_attributes: Vec<xml::attribute::OwnedAttribute>,
        mut source_namespace: xml::namespace::Namespace,
    ) -> Result<
        (
            Vec<xml::attribute::OwnedAttribute>,
            xml::namespace::Namespace,
        ),
        String,
    > {
        Ok((source_attributes, source_namespace))
    }
}
pub struct TPath {
    #[yaserde(text)]
    pub content: std::string::String,
}

Here is the code I'm using to derive, in case there's something wrong with it:

#[macro_use]
extern crate yaserde_derive;

use std::io::prelude::*;
use xml_schema_derive::XmlSchema;
use yaserde::{YaDeserialize, YaSerialize};

#[derive(Debug, XmlSchema)]
#[xml_schema(
    source = "https://docs.oasis-open.org/odata/odata-csdl-xml/v4.01/os/schemas/edm.xsd",
    target_prefix = "edm"
)]
struct EntityDataModel;

[MarcAntoine-Arnaud]

Hello @tobz1000 ,

I think it's a prefix issue, I have to look on it in details.
In this case, TPath is defined locally but it's referenced with the prefix edm that is defined at the beginning xmlns:edm="http://docs.oasis-open.org/odata/ns/edm"

I think it's possible that xml-schema does not handle correctly that.
I'll test that when I have more time ...

Marc-Antoine

[NelDav]

I have the same Issue with slightly differences. The error message only tells me that std::fmt::Display is not implemented.
Furthermore, I do not define any prefix.
Only want to let you know, that the issue varies in different cases.

Unfortunately I cannot provide the whole schema file, but I try to provide the relevant parts if you need.

I get the following error message:

error: proc-macro derive panicked
 --> src\main.rs:9:17
  |
9 | #[derive(Debug, XmlSchema)] 
  |                 ^^^^^^^^^
  |
  = help: message: not implemented
  = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0277]: `StorageType` doesn't implement `std::fmt::Display`
 --> src\main.rs:9:17
  |
9 | #[derive(Debug, XmlSchema)] 
  |                 ^^^^^^^^^ `StorageType` cannot be formatted with the default formatter
  |
  = help: the trait `std::fmt::Display` is not implemented for `StorageType`
  = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead
  = note: required because of the requirements on the impl of `std::fmt::Display` for `&StorageType`
  = note: required by `std::fmt::Display::fmt`
  = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)

My code is nearly the same, you provided on the cargo site:

#[macro_use]
extern crate yaserde_derive;

use std::io::prelude::*;
use xml_schema_derive::XmlSchema;
use yaserde::{YaDeserialize, YaSerialize};

#[derive(Debug, XmlSchema)] 
#[xml_schema(source = "target/feat/Schema.xsd")]
struct MySchema;

Note, that I do not define any target_prefix because if I do #[xml_schema(source = "target/feat/Schema.xsd", target_prefix = "xs")], I get the following error:

error: proc-macro derive panicked
 --> src\main.rs:8:17
  |
8 | #[derive(Debug, XmlSchema)] 
  |                 ^^^^^^^^^
  |
  = help: message: a prefix attribute, but no target namespace is defined, please remove the prefix parameter

[NelDav]

After some further research I think the problem is that the macro #[yaserde(rename = "Storage")] needs the implementation of std::fmt::Display to serialize the struct StorageType.
I don't know how #[yaserde(rename = "Storage")] is intendet to work, so I don't know if there is a bug in yaserde or in xml-schema.